How can I open .ENC files with Mountain Lion

I am new to iMac and having trouble already. By email, I have been sent a document containing words but it has a .ENC extension which I can't open. Doing a search for .ENC extensions I have found four different results. One saying it is a video, which is obviously not correct. Another says that my system is corrupted in some way and has invalid registry entries. Another says it is associated with Black Ice Evidence. And yet another says it is an encrypted file. If it is caused by invalid registry entries, how I clean the registry? I was told iMacs don't need the sort of cleaning that Windows did.